Carbon farming should consider more than carbon

Research led by CSIRO has shown that carbon farming schemes, which pay landholders for planting trees to absorb carbon dioxide, should consider other benefits such as the reversal of land clearing and the restoration of ecosystem services, including pest control, pollination and soil and water conservation.

At the same time, the schemes could have harmful effects, such as degrading ecosystems and causing food supply problems, if the benefits and disbenefits from revegetating agricultural landscapes are not taken into account. Thus, ‘best practice’ carbon farming is needed if farmers, landholders and communities are to realise the full benefits.

Tree plantings on degraded or unused land along fences, roads or at field margins can provide many co-benefits.

Dr Brenda Lin and her CSIRO colleagues used land-use models to assess a variety of ways that people have attempted carbon farming. She noted, “Policies aimed solely at maximising carbon storage may not produce additional agricultural and environmental benefits and may even produce unwanted outcomes for farmers, landowners and communities.

“For example, studies of past revegetation in agricultural landscapes show that in some locations, intensive single-species (or monoculture) plantations can affect water flows, increase invasive pests and lead to biodiversity loss, be fire-prone and have poor growth rates. Poorly located vegetation could reduce the availability of land for food production.”

But Dr Lin said there are several alternatives which will provide benefits beyond carbon sequestration, including planting strips of trees on farms, agroforestry - integrating trees into cropping systems - and revegetation of marginal or crop land.

“By revegetating unused, marginal or degraded cropping land, using multiple species of trees and shrubs, we could see improvements to pest control, pollination and water quality, increased wind protection and reduced soil erosion and salinity,” she said.

She noted that remnant native vegetation patches, if well managed, support a range of insect and spider predators and wasps that can attack pests of grain crops.

The research highlights the need for the organisers of carbon farming schemes to better understand the private, public and shared benefits and trade-offs. Dr Lin and her colleagues hope for local inhabitants to be involved in future policy decisions, as they can draw on their local knowledge of which trees are likely to thrive.

The research has been published in the journal BioScience.